Titanium nitride (TiN.sub.x, x.about.1) films have properties that make such films of interest in semiconductor device manufacture. Among the properties are hardness approaching that of diamond, a high melting point (about 3000.degree. C.), inertness to many chemicals and solvents, and good electrical conductivity. TiN.sub.x films are used as diffusion barriers in Si-based devices (typically between a Ti-silicide layer adjacent to the Si substrate and the W ohmic contacts). TiN.sub.x films are also used in the multilayer gate metalization in GaAs/AlGaAs HEMT devices, and in Schottky and ohmic metalization schemes in GaAs device technology.
Prior art TiN.sub.x films have been deposited by reactive sputtering of Ti in a Ar-N.sub.2 atmosphere, by evaporation of Ti in the presence of N.sub.2 (followed by a 700.degree.-900.degree. C. inert gas anneal), and by reduction of a TiSi.sub.2 layer by NH.sub.3 at 900.degree. C. Chemical vapor deposition (CVD) techniques have also been previously used to deposit TiN.sub.x. The CVD techniques used were atmospheric pressure CVD (APCVD) and low pressure CVD (LPCVD). See J. Klein et al., Proceedings of the 6th International IEEE VLSI Multilevel Interconnection Conference, p. 494 (1989); and A. Sherman, ibid, p. 497.
Although CVD of TiN.sub.x films is applicable to Si-based devices, it is of particular interest in conjunction with III-V compound semiconductor technology, due to the sensitivity of III-V-based devices to surface degradation during processing. The TiN.sub.x films typically are deposited by reacting TiCl.sub.4 and NH.sub.3 at 450.degree.-700.degree. C. at pressures from 0.1-0.3 Torr, and typically contain substantial amounts of carbon and/or O.sub.2.
Recently, R. M. Fix et al (Proceedings of the Materials Research Society Fall Symposium, Boston, Mass. 1989); and Chemical and Materials, Vol. 2(3), p. 235, 1990) have, inter alia, reported the deposition of TiN.sub.x by APCVD at 200.degree. C. on Si, vitreous carbon, glass, stainless steel and plastic substrates using metalorganic CVD (MOCVD).
Prior art techniques for TiN.sub.x deposition result in "blanket" deposition, namely, deposition on all (appropriately oriented) exposed portions of the substrate. Consequently, prior art TiN.sub.x layers generally are patterned subsequent to their deposition. For reasons that include process simplification and reduced cost, it would be highly desirable to have available a technique for selectively depositing TiN.sub.x on a semiconductor body. It would be particularly desirable if such a technique did not comprise a high temperature (e.g.&gt;500.degree. C.) step, and did not expose the semiconductor body to energetic particles capable of damaging the surface. This application discloses such a method.